Diamond charged saw blade and method of making same



Y seprn 24, 194s.

T, L ONGBOTHAM DIAMOND CHARGED SAW BLADE AND METHOD 0F MAKING SAME Filed March 4, 1944 Patented sept. 24, 1946 UNITED STATES PATENT OFFICE DIAMOND CHARGED sAW BLADE AND METHOD oF MAKING SAME y Thomas Longbotham, Portland, Oreg. Application March 4, 1944, Serial No. 524,982

Claims. l

This invention relates generally to the art of saw makingY Yand particularly to va diamond charged metal bonded saw blade.

'Ihe'main object of this invention is to produce a saw bladeof the type referred to in which the particles of diamonds are so thoroughly held within the periphery of the saw as to renderfit extremely dilcult to become dislodged and thereby lost.v Y

The second object is to devise asawblade of the class describedl which can lbe economically produced and which will operate for long periods of time in diflicult materials without -any necessity for dressing same. Y f

The third object is to so dispose the diamond particles-in atortuous band laround the` Vwheel perimeter in a manner that each bendl of the tortuous band shall project laterally through'the rimvof the wheel, `thereby providingta clearing out and protecting the-wheel itself against lateral wear. Y n

A further Objectis toso ,charge a metal vdisc with diamond dust that'the charging operation increases somewhat the thicknessof the cutting the notches or grooves are closed after being" filled with abrasive, that they actually bond the abrasives into the metal itself, not merely by trapping them in place as is the present custom, but by interlacing the abrasive in a zigzag fashion around the wheel and by allowing it to project laterally from the sides of the whee1`at the notch junctions.

I accomplish these and other objects in the manner set forth in the following specification as illustrated in the accompanying drawing, in which:

Fig. 1 is a fragmentary view of a saw blade.

Fig. 2 is a fragmentary end elevation of Fig. l.

Fig. 3 is a greatly magnified edge View of a small portion of the saw blade rim showing the uncharged tortuous curve.V

Fig. 4 is a fragmentary side elevation of Fig. 3.

Fig. 5 is a fragmentary transverse section taken along the line 5-5 in Fig. 3. f

Fig. 6 is aimagnied view of the saw rim showing the tortuous groove charged with abrasive and partially closed.

Fig. '7 is a side elevation of Fig. 6.

Fig. 8 is a view similar to Fig. 6 showing the wheel after a nal closing operation' has been performed. f Y

Fig.y 9 isa side elevation of Fig. 8.

.Before enteringinto an explanation offthisV invention, it is of course understood that diamond charged wheels have beenin use for a long time. Various methods havebeen adopted for charging these wheels, butas far as is known, all of these methods have onev ,common fault-the ydiamond particles are trapped into grooves or notches by an extruding action on the outer limit ofv the saw, and when the extruded metal isworn away, the particles of diamonds are free vto escape and are not only lost, but actually serve to break down ther wheel itself when theloosened particles of diamond pass through the cut between the saw and the work. l

With the saw which I am about to describe, there is practically no extruding operation'performed'but a diagonal severing of the metal yand a lateral bending resulting in the formationof. what are comparablev with saw'tee'th having Aa considerable setf In addition thereto, the abrasive is caused to project through the slots formed between the teeth providing thefnecessary lateral cutting action. l j

Referring in detail to the drawing, there is shown a circular blade Il), preferably of a soft steel with a tinned surface. In therimgrll of the blade I0 are formed the alternating diagonal slots I2, whose connecting ends terminate in the slots I3 at each side of the blade I0. The metal from the slots I3 form the lands I 4 of the teeth I5, whose diagonal faces I6 form the sides of a tortuous passageway around the rim II. Owing to the manner in which the teeth I5 are formed, there is a slight distorting action which inclines the edges II slightly away from the side I8 of the blade I0.

After the blade Id is completely notched, the faces I6 and lands I4 are coated with a suitable adhesive I9, preferably of the rubber base type. The adhesive covered surfaces are now charged with diamonds 20 and the teeth I5 are givenv a preliminary closing movement as shown in Fig.. 6. They are then finally rolled to gauge as shown in Fig. 8, causing the entrapped abrasive 2!! to be imbedded in the faces I4 and I6 without any danger of their becoming dislocated and lost.

When it is remembered that diamonds do not wear out but fall out of diamondA charged saw blades, it can be seen that the main difficulty with such devices has been overcome and extensive tests with these blades on the hardest types of quartz and other materials proves that they will saw faster and last longer than any known blade of the same type.

Since the blade l@ is necessarily quite thin and laterally flexible, it can be seen that the slightest irregularity on the face of the rim il would cause the saw Iblade to vibrate and run, thereby unduly wearing the saw and retarding the cutting operation. To overcome this diiliculty I provided a pair of guides 2| mounted on the brackets 22, which are preferably yielding in order that the guides 2l may firmly support the plate Il) without unnecessary wear or retarding action.`

While the edges and surfaces of the parts coming in contact with the adhesive l!) and abrasive 20 are illustrated as being straight and smooth, they are actually quite rough when examined under a glass, all of which tends to iinprove the bonding action occasioned by the hard diamond particles being pressed between the relatively soft metal surfaces I6.

It will be understood that the exact angle of the faces IG as well as the size of the lands I4 is not important, but can .be varied considerably Without departing from the spirit of this invention.

Although the land I4 has been shown to an appreciable size, in actual practice it is made very small, the purpose being to leave only a narrow slit through which the confined diamond may project and by means of which it is held against escape.

It can be readily seen that by making the line of abrasives in the form of a tortuous band, I have not only improved the bonding action but I have greatly increased the amount of abrasive with which a given wheel can be charged, thereby increasing the cutting action and adding to the life of the saw itself.

Saws of this type need not be dressed at all, but may be "used indenitely or until the entire diamond bearing portion thereof is Worn away, without any attention. In fact, they seem to cut smoother and faster after having been in use a considerable period of time.

While I have thus illustrated and described my invention, it is not my desire to be limited to this precise form, but I do intend to cover all such forms and modifications thereof as fall fairly within the appended claims. y

I claim:

inclined slots formed therein, the ends of which join to form a zig Zag passageway, said connecting ends opening through the `sides of the wheel,

' said groove and lateral openings being charged Iwith diamonds, the diamond bearing portion of the blade having a greater thickness than does the lateral of the blade.

3. A method of making diamond charged saw blades consisting of notching the edge of said blade diagonally with relation to its axis of rotation, succeeding notches being in opposite directions, the junctions'of each pair of notches extending through the sides of the blade at the rim thereof, then coating the internal face of the groove with an adhesive, then depositing diamonds in said adhesive, then compressing the sides of said groove upon said diamonds.

4. A method of charging saw blades with cliamonds, consisting of forming a tortuous broken groove in the periphery of a disc by spreading the material therein diagonally along its edges, forming openings in the side of the disc joining with the groove at its bends, then coating the walls of the groove with a rubber cement, then depositing diamond dust in the cement, then removing any diamonds not adhering to the adhesive, then closing the groove 'walls to co-nne the diamonds therein. Y l

5. A method of making diamond charged saw blades consisting of progressively forming a disc of soft steel, slitting the periphery of the wheel diagonally in alternate directions to form a zig zag groove around the blade in a manner to cause the inner side of said groove to flare outwardly, then coating the interior of said groove with adhesive, then charging the adhesive with diamonds, then closing the walls of said grooves upon said diamonds, then compressing the diamond bearing portion of the blade.

THOMAS LONGBOTHAM. 

